1. Field of the Invention
The present invention relates generally to slide fasteners, and more particularly to a slider for a slide fastener.
2. Prior Art
A known slide fastener comprises a pair of fastener stringers including a pair of stringer tapes carrying along their inner longitudinal edges a pair of rows of fastener elements attached by holding threads to the respective tapes, each row of fastener elements being in the form of a coiled plastic filament. Each of such fastener elements has a substantially oval contour and it hence tends to be angularly moved or tilted in a slider when a lateral pull is exerted on the corresponding tape. This often results in an unstable and defective coupling of the opposed rows of fastener elements.
To solve this problem, an improved slider has been proposed in which a pair of lateral edge flanges on an upper wing has a pair of corner ridges each extending along an inner base portion of the respective flange through the length thereof at a longitudinally uniform hight. Each of the corner ridges has a fastener-element pressure surface engageable with upper leg portions of the respective row of fastener elements to restrain the fastener elements from being tilted in a guide channel of the slider, the upper leg portion facing the interior side of the upper wing.
However, this slider creates another problem that a leading end of the opposed rows of fastener elements, when a pair of opposed fastener stringers (or a fastener chain) is threaded through the slider in the manufacture of slide fasteners, can be easily obstructed by the front ends of the corner ridges. Accordingly, with such prior art arrangement a proper and smooth threading of the opposed fastener stringers through the slider is difficult to achieve.